Refrigeration



E. B. MILLER REFRIGERATION Sept. 24, 1929.

Filed Aug. 3, 1929 3&

m. M M M .p M T W T z z M j. a v d i A 6 T i J V j a j z b fi 4 a fi G aM w w/ M z V461/11/77 Pa Head'e/ gwwnto'o Patented Sept. 24, 1929 gUNITED STATES PATENT OFFICE ERNEST B. MILLER, OF BALTIMORE, MARYLAND,ASSIGNOR TO THE SILICA. GEL- CORPORATION, OF BALTIMORE, MARYLAND,

A oonromrron or MARYLAND REFRIGERATION Continuation of applicationsSerial No. 675,929 filed November 20,

23,1924, and Serial No. 236,322, nled November as, 1921, and in GreatBritain and Irish rm State October 25, 1924. This application filedAugust 3, 1929. Serial No. 383,319.

refrigerating effect is obtained without .any

1 chemical action.

Another'object is to provide an apparatus so simple that it can bemanufactured to sell at a price that is within the reach of the majority of the people.

Briefly stated, the invention consists in adsorbing, in a porousmaterial, vapor from a liquid, the adsorption taking place substantially in .the absence of permanent gases. The evaporation of the liquidgives the refrigerating effect. The porous material adsorbs the vapor inits pores andthereafter the material is treated to liberate the adsorbedvapor, so that the material may be used for another adsorbing cycle.

A second form of the invention aims to provide a method and apparatus ofthe type described above but more particularly adapted for embodimentinsmall units, such as used with the usual household refrigerator.

The principal feature of this second form of the invention resides inthe elimination of all pumpsand machinery, the only requirements foroperating the apparatus being a supply of Water and heat.

An apparatus for carrying out the method of thesecond form of theinvention comprises an evaporator, an adsorber charged with a y porousmaterial, said adsorber being in communication with the evaporator, bothsaid parts being substantially free from permanent gases, whereby vaporevaporating from liquid in the evaporator is adsorbed by the material,giving a refrigerating effect. In order to use the vapor over again, acondenser, also substantially free of permanent gases,

has communication with the evaporator and the adsorber. Means isprovided to liberate the vapor from the porous material causing it topass to the condenser where it is liquefied and then returned to theevaporator. I The adsorbing material should have very fine poresin orderto adsorb the vapor at low pressures. More specifically stated thematerials should have pores of such size that they Will adsorb watervapor under static conditions to such an extent as to contain not lessthan substantially 10% of their own Weight of water when in equilibriumwith Water vapor at 30 C. and 22 mm. of mercury.

Other objects and features of novelty will 1923, Serial No. 688,020,filed January be apparent from the description taken invention.

Referring to Figure 1 of the drawings which illustrates one form of theinvention, a

closed vessel forming an evaporating chamber 10 is in communication withan adsorber 11 by means of a conduit 12. The evaporator 10 contains-aliquid such as brine or water which is evaporated to obtain therefrigerating effect. The adsorber 11 is of any suitable form and ischarged with a porous material 13 preferably in adsorb the vapor rom theliquid in its pores.

The pores of the adsorbing material required in the present method areultramicroscopic, so that it is a very difiicult matter to accuratelydetermine and define their size. One satisfactory method of comparingthe size of the pores in two bodies and also the total volume of thesepores consists in determining the amount of water that one gram of eachbody will adsorb when exposed to water vapor under definite condition oftemperature and partial pressure. The amount of water vapor adsorbed bya porous body at a given temperature and partial pressure depends bothupon the size of the diagrammatic illustration of a refrigeratingapparatus adapted for carrying out the method of the second'form of theinranular form, adapted to pores-and upon the total interior volume of.said pores. Thus,"two' materials may have pores such that the internalvolume of the pores in a gram of one material is the same one having thesmaller pores will adsorb vapor at lower partial pressures than theother. In other words very small pores are required in order to adsorbvapors at low partial pressures... To illustrate, assume that a buildingbrick has the same internal volume as an equal weight of silica gel. Thebrick, however, will adsorb substantially no water vapor at pressuresbelow atmospheric, whereas the silica gel will adsorb large amounts atvery low pressures. 'This is explained as follows. A liquid that wets acapillary tube will rise in the tube above the level of the surface ofthe liquid surrounding the same,

the extent of the rise varying with the diameter of the tube. The vaporpressure of the liquid insidethe tube is smaller than the vapor pressureat the level surface of the liquid-outside the tube. This lowering ofthe vapor ressure by the liquid within the capillary tu e is notappreciable until the diameter of the tube is extremely small, and thesmaller the bore of the tube, the greater the decrease in vapor,pressure. Consequently the vapor pressure within the pores of a bodyhaving small pores is less than in a body having large pores, with theresult that the body having the smaller pores will adsorb vapors andgases at lower partial pressures.

Thus, by determining the amount of a given material, water 0 may beadsorbed by each of two porous bodies under the same condition oftemperature and partial pressure, I have a means of comparing the sizeand volume of the pores in the two adsorbents. For example, a sufficientpercentage of the total internal volume in silica gel is made up of suchsmall pores that the gel will adsorb water to such an extent that itwill contain, at 30 C. about 21% of-its own weight of water when inequilibrium with water vapor at a partial pressure of substantially 22mm. of mercury.

Materials suitable for the present invention should have pores of suchsize that the material will adsorb water vapor to such an extent as tocontain not less than-about 10% of its own weight of water when inequilibrium with water vapor at 30 C. and a partial pressure ofsubstantially 22 mm. of mercury.

Preferably silica gel is employed as the porous material. As stated thismaterial has pores of such size that it will adsorb water vapor to suchan extent as to contain at least 21% of its own weight of water when inequilibrium with water vapor at 30 C. and a partial pressure ofsubstantially 22 mm. of

1' example, which or more of the foregoing andother oxides.

At the present time, however, I have found silica gel to be themostsatisfactory adsorbent for vapor from the liquid in the evaporator.In stating that the adsorbents for the present invention should adsorbnot less than 10% of their weight of water vapor, I do not mean this isan exact line of demarcation between satisfactory and unsatisfactoryadsorbents.

The limit of 10% is intended to indicate in general about the maximumsize pores that can be employed with some degree of success. Of course,for best results materials having smaller pores should be used.-

.The adsorbing action is a purely physical phenomenon, and involves nochemical action. Any body or material having pores of the size andquantity defined herein will act as stated and is suitable for use as anadsorbent. in the present apparatus:

A porous adsorbent may adsorb a vapor or as either statically ordynamically. In dynamic adsorption there is relative movement of theadsorbent and the vapor. For example, the vapor may be adsorbed from astream of gases passing through a bed of the adsorbent.

In static adsorption there is no relative movement of the vapor andadsorbent. For example, the adsorbent is disposed in a closed vesselcontaining the vapor to be adsorbed. Thus, when a dish containing theadsorbent is placed in a closed jar having sulphuric acid therein, theadsorbent will take up water vapor until it is in equilibrium with thewater vapor in the jar.

Van Bemelen and others have studied the adsorption of water vapor bysilica gel statically and found that it required a long time for silicagel to come into equilibrium with the vapor around the gel. Inmost casesit took weeks, and sometimes months.

Later, as disclosed in Patent N 0. 1,335,348

it was discovered that silica gel would adsorb a vapor, dynamically,almost instantaneousl In the present invention, the adsorber is incommunication with the evaporator, and $0 the va or from the evaporatoris adsorbed statica ly bythe silica gel. From what was known, prior tomy invention, I reasoned that this adsorption would be so slow that itwould be impractical. I have discovered, however, that the adsorption israpid'provided there are substantially no permanent gases present. Inorder to carry on the adsorption in the absence of permanent gases Iprovide a v acuum pump14 in communication with the adsorber by means ofa conduit 15.

. After the adsorbing material has adsorbed vapor from the liquid in theevaporator, it may be freed of this adsorbed vapor an again used as anadsorbent. One method of thus freeing the adsorbent of its vapor, or asit is termed activating the material, is shown in the drawings. Hotgases from a furnace or other source 16 are conducted by means'of aconduit. 17 to the adsorber and these gases heating the adsorbentmaterial drive off the vapor that may be present in its pores, adischarge conduit 18 being provided, this conduit being connected to anexhaust fan 19.

In operation the valves 20 and 21 control- 'lin the activation of theadsorbing material are closed and valves 22 and 23 opened. The vacuumpump substantially removes'the permanent gases from Within the adsorberand evaporator, whereupon the liquid boils and the vapor given off isadsorbed by the porous material. This evaporation of'the' liquid withinthe evaporator of course produces a" refrigerating effect. After theadsorbing material has taken up vapor from the liquid in the evaporator,the, valves 22 and 23 are closed and valves 20 and 21 opened. Theexhaust fan 19 will then effect a flow of the hot gases through the bedof adsorbing material and liberate the vapor adsorbed thereby so thatthe adsorbing material is activated. After this has been done the valves20 and 21 will be closed and valves 22 and 23 opened wvhereupon theadsorbing material will again become active to take up vapor and producea refrigerating effect. Liquid to make up for that lost in activatingthe adsorbing material may be supplied to the evaporator through aconduit 24.

If it is desired to carry on the refrigerating effect without anyinterruption, then two adsorbers may be employed, one being'used toadsorb the vapor while the adsorbing material in the other is beingactivated. 'Thus, as shown, a second adsorber 13 at its upper end has aconduit 12 in communication with the conduit 12 leading to theevaporator and this conduit 12 has a valve 22 for controlling the flowtherein. At its lower end the second adsorber 18 by means of a conduit15 is in communication with the conduit 15 leading to'the vacuum pump,valve 23 being provided to control this conduit. This second adsorber isalso in communication with the conduit 17 leading to the furnace andwith the conduit 18 leading to the exhaust fan 19, valves 20 and 21being provided to control flow to or from said furnace and fan, respectively.

The operation of this second adsorber is exactly like the one alreadydescribed. When one adsorber is in communication with the evaporator,the other is cut off therefrom and is having its adsorbing materialactivated.

The second .form of the invention is shown in Figure 2 wherein a closedvessel forming an evaporating chamber 110 is in communicad tion with anadsorber 113 by means of a conduit 112. The evaporator 110' contains aliquid such as brine or water which is evaporated to obtain therefrigerating effect. The adsorber 113 is of any suitable form and ischarged with a porous material 114 preferably in granular form, adaptedto adsorb in its pores, the vapor from the liquid.

Suitable means, hereinafter described, is provided to liberate the vaporfrom the porous material, and this liberated vapor is condensed andreturned to the evaporator. For this purpose a condenser 125 isprovided, being in communication with the adsorber through a conduit 126and with the evaporator through a conduit 127. The condenser as well asthe conduits 126 and 127 are free of permanent gases. evaporator,adsorber, and condenser which form a closed pathfor the vapor aresubstantially free of permanent gases.

The permanent gases are exhausted from the parts just described in anysuitable manner. According to one method, this can be effected by meansof a vacuum pump, the

In other words the opening through which the apparatus hascommunicationwith the pump being sealed after the permanent gases havebeen removed. For this purpose, the valve 142 in conduit 112 might be athree-way valve, the third opening in the valve being adapted to beconnected with a pump. After the permanent gases have been exhausted,the valve will be turned to close the said third opening'and then thisthird opening might be sealed to prevent the admission of any gases. Of

or the vacuum be destroyed in any way, the

conduit connections to the evaporator, condenser and adsorber are allwelded to these parts respectively.

After the adsorbing material has adsorbed vapor from the liquid in theevaporator, it may be freed of this adsorbed vapor and can again be usedas an adsorbent. One method of thus freeing the adsorbent of its vapor,or as it is termed activating the material, is shown in the drawings.One or more coils lOO 128 are disposed in the porous material in in itspores.

condenser 125.

the adsorber, these coils, at one end through a conduit 129, and at theother end through a conduit 130, being in communication with a heater131. The heater may be of any suit able type. As shown it comprises acoil 140 having communication at its ends with the conduits 129 and 130respectively. A burner or any other source of heat 141 is disposed bencath the coil 140. A liquid such as water is supplied through the pipe132, a valve 133 being provided to control the flow. Preferably thispipe 132 is connected with the water supply in the house. The water inthe coil 140 is thus heated and flows through pipe 129 tothe coils 128within the adsorber and thence returns by conduit 130 to the heatingcoil 140. The hot water passing through the coils within the adsorberheats the adsorbing material thereby liberating the vapor adsorbed with-The water within the heater may be heated above the boiling point sothat the vapor will be rapidly driven off from the adsorbing material.After the porous material has been activated in this manner, the

valve 133 is opened thereby admitting. cold water from the water mainsof the house, and valve 134 is closed and valve 135 opened permittinrdischarge of the cooling water. Thus the coils 128 within the adsorbernow become cooling coils and reduce the temperature of the porousmaterial so that it will adsorb more efficiently. 1

The vapor liberated from the porous ma terial pases through the conduit126 to the Suitable means such as a valve 142 in conduit 112 may beprovided so that the vapors will not return to the evaporator throughpipe 112. If desired, this condenser may be cooled in any suitablemanner, as by means of a coil 136 supplied with cooling water from thewater mains of the housethrough pipe 137 this cooling water beingcarried off through a pipe 138. A valve 139 in pipe 137 may be providedto control the flow of the cooling water. Suitable means such as a valve143 may be provided in the conduit 127 so that communication between theevaporator and the condenser may be cut off when the vapor is beingadsorbed by the porous material.

To start the apparatus, valve 142 is opened and valve 143 closedwhereupon vapor from the evaporator is adsorbed by the porous materialin the adsorber. If desired, cooling water for the adsorber may beadmitted through pipe 132, the flow being controlled by valves 133 and135.- After the porous material has been, adsorbing the vapor for asufficient time, valves 142, 133 and 135 are closed. Then the heater 131is put into operation so that the water within the coils is heatedthereby activating the porous mateapparatus. The only manipulationrequired is to start and stop the heater 131 and operate certain valves142, 143. Although not shown, of course automatic means may be providedto operate these parts, the automatic means being thermostaticallycontrolled or not as desired.

While the invention has been disclosed using a refrigerant which isnormally a liquid it can be practiced equally as well by using a gas. Asa specific instance sulphur dioxide (S0 may be mentioned. If this gas ispumped into the system to completely fill the same and to exclude airand other permanent gases and is put under sufficient pressure, aportion of it will liquefy. The process will then operate as beforedescribed using however a positive pressure. Other suitable refrigerantseither liquid or gaseous may also be used.

In the claims, the words in the total absence of permanent gases areintended to signify that the permanent gases are removed to as great anextent as is practicable .with present day methods and apparatus.

This application is a continuation of the following applications:

675,929, Ernest B. Miller, refrigeration, Nov. 20, 1923; 688,020, ErnestB. Miller and Axel Benzon, refrigeration, Jan. 23, 1924;

236,322, Ernest B. Miller, refrigeration, Nov. 28, 1927.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. A method of refrigeration consisting in evaporating a liquid andadsorbing the vaporevaporating a liquid and adsorbing the vapor in thesubstantial absence of permanent gases, in a porous material havingpores of such size that it will adsorb water vapor under staticconditions to such an extent as to con-' tain at least 21% of its ownweight of water when in equilibrium with water vapor at substantially C.and a partial pressure of substantially 22 mm. of mercury.

, 3. A method of refrigeration consisting in evaporating a liquid andadsorbing the vapor in the substantial absence of permanent gases, insilica gel having pores of such size that it will adsorb water vaporunder static conditions to such an extent as to contain at least 21% ofits own weight of water when in equilibrium with water vapor atsubstantially 30 C. and a partial pressure of substantially 22 min. ofmer'curv'.

4. A method of refrigeration consisting in evaporating a liquid andadsorbing the vapot in the substantial absence of permanent gases, insilica gel having pores of such size that it will adsorb water vaporunder static conditions to such anextent as to contain at least 21% ofits own weight of water when in equilibrium with water vapor atsubstantially 30 C. and a partial pressure ofsubstantially 22 mm. ofmercury and thereafter freeing the material of the adsorbed vapor sothat it may again adsorb.

5. A method of refrigeration consisting in evaporating a liquid andadsorbing the vapor in the substantial absence of permanent gases, insilica gel having pores of such size that it will adsorb water vaporunder static conditions to such an extent as to contain at least 21% ofits own weight of water when in equilibrium with water vapor atsubstantially 30 C. and a partial pressure of sub tantially 22 mm. ofmercury and thereafter heating the gel to liberate the adsorbed vapor sothat the gel may again adsorb.

6. In apparatus of the character described, in combination, anevaporator adapted to contain a liquid to be evaporated, an adsorber incommunication therewith and charged with a porous material capable ofadsorbing rapidly vapor from the liquid only in the absence of permanentgases, said material having pores of such size that it will adsorb watervapor under static conditions to such'an extent as to contain not lessthan about 10% of its own weight of water when in equilibrium with waterVapor at substantially 30 C. and a partial pressure of substantially22mm. of mercury.

7. In apparatus of the character described, in combination, anevaporator adapted to contain a liquid to be evaporated, an adsorber incommunication therewith, and charged with a porous material capable ofadsorbing rapidly vapor from the liquid only in the absence of permanentgases, said material having pores of such size that it will adsorb watervapor nnderstatic conditions to such an ex-' tent as to containat least21% of its own weight of water when in equilibrium with Water vapor atsubstantially 30 C. and a partial pressure of substantially 22 mm. ofmercury,

8. In apparatus of the character described, in combination, anevaporator adapted to contain a liquid to be evaporated,tan adsorber incommunication therewith and charged with silica gel having pores of suchsize that it will adsorb water vapor under static conditions to such anextent as to contain at least 21% of its own weight of water wheninequilibrium with water vapor at substantially 30 C. and a partialpressure of substantially 22 mm. of mercury.

9. A method of refrigeration consisting in evaporating a salt solutionand adsorbing the water vapor in the substantial absence of permanentgases, in a hard porous gel having a pore structure like that of silicagel.

A 10. A method of refrigeration consisting in evaporating a saltsolution and adsorbing the water vapor in the substantial absence ofpermanent gases, in a hard porous silica gel.

11. A method of refrigeration consisting in evaporating a liquid andadsorbing the vapor in the substantial absence of permanent gases, in aninorganic material having pores of such size that it will adsorb watervapor under static conditions to such an extent as to contain not lessthan about 10% of its own weight of water when in equilibrium with watervapor at substantially 30 C. and a partial pressure of substantially 22mm. of mercury.

12. A method of refrigeration consisting in evaporating a liquidand-adsorbing the vapor in the substantial absence of permanent gases,in an artificial porous material having pores ofsuch size that it willadsorb water vapor under static conditions to such an extent as tocontain at least 21%of its own weight of water when in equilibriumwithwater vapor at substantially 30 C. and a partial pressure ofsubstantially 22 mm. of mercury.

13. A method of refrigeration consisting in evaporating a liquid andadsorbing the vapor, in the total absence of permanent gases, in aporous material having pores of such size that it will adsorb watervapor under static conditions to such an extent as to contain not lessthan about 10% of its own weight of water when in equilibrium with watervapor at substantially 30 C. and a partial pressure of substantially 22mm. of mercury, with such rapidity as to cause cooling of the liquidfrom which the vapor is evaporated, liberating the vapor thus adsorbedand returning thesame for re-use.

14. The method according to claim 13 wherein the adsorbing material isagel having pores of such size that it will adsorb water vapor understaticconditions to such an extent'as to contain at least 21% of its ownweight of water when in equilibrium with water vapor at substantially 30C. and p a' partial pressure of substantially 22 mm. of mercury.

15 Apparatus of the character described including in combination, anevaporator, an adsorber charged with a porous material capable ofadsorbing rapidly vapor from a liquid only in the total absence ofpermanent gases, and a condenser, said parts being in communication andsealed against the entrance of any air, said parts also being totallyfree from permanent gases, the evaporator being charged with a liquidcapable of being evaporated at the temperatures desired and'the porousmaterial in the adsorber having pores of such size that it will adsorbwater vapor under static conditions to such an extent as to contain notless than about 10% of its own weight of water when in equilibrium withwater vapor at substantially 30 C. and a partial pressure ofsubstantially 22 mm. of mercury with such rapidity as to cause coolingof the liquid from which the 2:1 vapor is evaporated.

'16. A method of refrigeration consisting in evaporating a liquid andadsorbing the vapor, in the total absence ofpermanent gases, in anartificial porous material having pores of such size that it will adsorbwater vapor under static conditions to such an extent as to contain notless than about 10% of its own Weight of water when in equilibrium withWater vapor at substantially 30 C. and a partial pressure ofsubstantially 22 mm. of mercury, with such rapidity as to cause coolingof the liquid from which the vapor is evaporated, liberating the vaporthus adsorbed and returning the same for reuse.

17. A method of refrigeration consisting in evaporating a liquid andadsorbing the vapor, in .the total absence of permanent gases, in aninorganic porous material having pores of such size that it will a'dsorbwater vapor under static conditions to such an extent as to contain atleast 21% of its own weight of water when in equilibrium with watervapor at substantially 30 C. and a partial pressure of substantially 22mm. of mercury, with such rapidity as to cause cool ing of the liquidfrom which the vapor is evaporated, liberating the vapor thus adsorbedand returning the same for re-use.

In testimony whereof I hereunto aflix my signature.

ERNEST B. MILLER.

